1. Field of the Invention
This invention relates to improvements to methods and apparatus for capturing floating fluid pollutants spilled into streets, parking lots and streams. More particularly, this invention relates to an underflow dam unit which traps floating pollutants either before or after they escape into a ditch or stream.
2. Description of Related Art
Recent amendments to the federal Clean Water Act and other environmental laws emphasize increased control of non-point source emissions, particularly for street and parking lot runoff tainted by vehicles. Currently parking lots and streets have been equipped with catch basins strategically located to collect runoff and deliver it to open ditches or municipal storm sewer systems, with no accommodation for entrapping pollution before it enters the sewer. Responsibility for control of such emissions, however, more and more is being placed upon property owners and engineers designing runoff systems. A need exists for a cost effective way to capture pollutants at such non-point source situations before they enter the storm sewer systems.
Particular to electric utilities is the need to recapture transformer oil spilled in substations and from oil-filled devices installed on distribution lines. As commonly is done in refinery tank farms, substations increasingly are built with levee systems to trap oil from large power transformers and other oil-filled equipment. Levee systems are undesirable in utility substations, however, because maintenance vehicles frequently must have unobstructed access to power equipment, and levees get in the way. Further, levees may be damaged by the power vehicles and tend to crack on their own without regular maintenance. A need exists for a better way to entrap oil spilled in such installations.
Regardless of the source of pollutants, spills escaping into nearby ditches or streams must be reclaimed. A common way of doing so is to build a temporary levee or embankment across the stream. While water pools behind the levee, piping is buried through the levee with its inlet end below the water surface. The piping allows subsurface water to escape downstream while holding back most of the floating pollution. Such an installation is depicted in FIG. 4. The major disadvantages of such systems include the delay typically required for construction, acquisition of appropriate and adequate piping for each unique installation, and the need for large levees to retain the pollution during the delay. A need exists for an improved system for emergency spill control.